Process for the manufacture of diazotype copies



United States Patent 2,741,558 PROCESS FOR THE MANUFACTURE OF DIAZUTYPE COPIES Theodorus Peirus Wilhelmus Sanders, Venlo, and

Johannes Henricus Andreas Wilder's, Blericlt, Netherlands, assignors, by mesne assignments, to Chemische Fabriek L. Van der Grinten N. V., Venlo, Netherlands, a corporation of the Netherlands No Drawing. Application March 11, 1952, Serial No. 276,061 12 Claims. (Cl. 95-88) The invention relates to a process for the production of diazotype copies by selective exposure (i. e. exposure to light of locally different intensity) of one-component diazo film layers sensitised with a para-aminobenzenediazo compound.

The development of diazotype materials can be effected in known manner by immersing the material in a bath of a developer or by applying to the material a thin layer of developing liquid (so-called semi-wet development). The latter method is in practice generally carried out mechanically.

These methods of development of diazotype copies are usually applied when the diazo layer is of the one-component type, i. e. does not contain an azo coupling component; the developer then contains, in addition to buifer salts, one or more azo coupling components which cause the formation of azo dyestulf by reaction with the undecomposed diazo compound.

In this type of diazotype printing use is preferably made of diazo compounds and azo coupling components which have a fairly high coupling activity, or one may use strongly alkaline developers (which is often inad visable). One may naturally use diazo compounds with slightly less coupling activity in combination with a very active azo component or, conversely, combine an azo dyestuif component with less coupling activity with a diazo compound with greater coupling activity.

The azo dyestuffs formed should not bleed in the developer.

Substances which in general have sufiicient coupling activity for the practical application of thin-layer development include p-diazo-diphenylamine, p-diazo-ethylbenzylaniline, p-diazo-di-normal-butylaniline, p-diazoortho-chlorodiethyl-aniline, the p-diazo-Z.S-dialkoxy-acyl anilides, and many others. The p-diazo-2.5-dialkoxyacyl anilides are very active, and even suitable for development at pH about 7.

Examples of diazo compounds which in practice are preferably not used for diazotype printing with thin-layer development, because they have insufiicient coupling activity, are p-diazo-aniline, p-diazo-monomethylaniline and p-diazo-dimethyl-aniline. Compounds such as p-diazo-diethylaniline and p-diazo-dipropylaniline are on the borderline for practical application by thinlayer development.

As azo coupling components having sufiicient coupling activity for thin-layer development there may be mentioned betanaphthol, phloroglucinol, resorcinol, l-phenyl- 3-methyl-5-pyrazolone (very active) and acetoacetanilide; azo components with insufiicient coupling activity are phenol and 2.3-di-hydroxynaphthalene-o-sulphonic acid.

By the term diazo film layer as used herein is meant a special type of diazo layer. The generic term diazo layer is also used when the diazo compound is simply spread out on the fibres of a paper surface as a driedup coating, perhaps in the form of a very thin, uneven and possibly discontinuous diazo surface. A diazo film layer in accordance with the present invention has the character of a true layer of measurable thickness. A diazo film layer need not be equally thick throughout; it

2,741,558 Patented Apr. 10, 1956 may, for example, show a relief. Such a diazo film layer comprises material which will be referred to hereinafter as film-forming material.

The diazo film layers must be resistant to treatment with the thin layer of aqueous developer, i. e. the filmforming material employed must not present any serious difliculty when treated with an aqueous liquid, for example by reason of melting, dissolving or becoming objectionably sticky as is the case with layers of gum, alkyl cellulose, soft gelatine and similar substances. 0n the other hand, it must be capable of readily accepting and absorbing the thin layer of developer.

The diazo film layer will usually be mounted on a support; in special cases it may, however, also be independent.

It has now been found that by exposure of various paminobenzene-diazo compounds certain products (hereinafter to be called photochemical decomposition products) are formed Which are capable of reacting at room temperature with aqueous solutions of diazo compounds with a pH of over 7, whereas the photochemical decomposition products of other p-aminobenZene-diazo compounds do not have this eifect, or only slightly so. The said action, when it takes place, proceeds more rapidly the higher the pH of the solution and takes place to a measurable extent, for example, at pHs ranging from 9 to 10.

The action of the photochemical decomposition products of the various p-aminobenzene-diazo compounds may be compared by testing them with the aid of a compound of this class which itself undergoes only very slight changes if any, when stored under the conditions hereinafter described. It has been found that p-diethylaminobenzene-diazonium chloride satisfies this requirement. If a 0.002 normal solution of this compound in water, to which sodium carbonate has been added to bring the pH to 9.5, is allowed to stand for 15 minutes at 18 C. (without exposure to light), the content of diazo compound in the solution is but very slightly altered. The decrease of the diazo content is found to be about 2% and this serves as the control test.

The action of the photochemical decomposition products of p-aminobenzene-diazo compounds may be tested by adding the photochemical decomposition products of the p-aminobenzene-diazo compoundsto be tested to a similar solution as in the control test. In order to obtain comparable results, the test is carried out in the following manner:

A weakly acidic 0.004 normal solution of the diazoniurn compound in question is taken and exposed to light until all the diazo compoundhas been decomposed. The liquid obtained is mixed with an equal volume of 0.004 normal p-diethylaminobenzenediazonium chloride solution, and brought to a pH of 9.5 by the addition of sodium carbonate. The mixture is now allowed to stand for 15 minutes at 18 C., after which the remaining quantity of p-diethylaminobenzene-diazonium compound is determined.

The results of tests with a number of diazo compounds are set out in the following table:

purpose of the invention the photochemical decomposition products are called active when they reduce the diazo content by at least 50% under the conditions of the test just described.

It has further been found that under certain conditions it is possible to obtain important valuable effects in the reproduction of continuous tones by means of paminobenzene-diazo compounds of which the photochemical decomposition products are active in the above sense.

According to the present invention a process for 'the production of diazotype copies comprises selectively exposing (e. g. through a continuous tone diapositive) a one-component diazofilm layer material which is suitable for development with a liquid and which contains a p-aminobenzene-diazo compound which yields an active photochemical decomposition product (as hereinbefore defined), rendering the copy alkaline and thereafter developing it by treatment with an aqueous solution of an azo coupling component.

By this process the images obtained in the diazo film layer reproduce the medium tones, and particularly those in the more dense areas of the image, in a richer gradation than is obtained without the intermediate treatment of rendering the material alkaline, or than is obtained with the use of p-aminobenzene-diazo compounds of which the photochemical decomposition products are inactive in the sense defined- 'In other words, the result obtained is a substantially softer gradation, or lower contrast, than has been hitherto possible, so that excellent tonal reproductions may be made of continuous tone originals.

In the foregoing statement of the invention the term diazo compound is to be understood to include mixtures of such compounds which have similar properties.

Particularly good results are obtained when the process according to the invention is applied to diazo film layers containing .diazo compounds. of the following general for-- mula:

, in which X is an anion and R1 and R2 are alkyl radicles having together 10, 11 or 12 carbon atoms,.each .alkyl radicle containing at least 4 and at most 7 carbon atoms, and not more than one of the two having a side chain attached to the alpha carbon atom.

The intermediate alkaline treatment may be advantageously'carried out by exposing the copy for some time to moist ammonia fumes. Alternatively, a thin layer of an alkaline liquid may be applied to the copy between exposure and development. In this intermediate treatment, of course, no azo component is present. The intermediate treatment may be followed almost immediately by development with a thin layer of a developer containing an active azo coupling component. The intermediate treatment with alkali, even when carried out with ammonia fumes, is preferably confined to the minimum necessary to secure the desired result. When the intermediate treatment is carried out with an alkaline liquid, this should be effected in such a way that the diazo image will lose as little as possible of itssharpness owing to bleeding. For this reason this treatment is preferably carried out according to the thin-layer method, with a layer of liquid which is as thin as possible (for example 7 .g. per square metre). For the final development with the developer containing the azo component, the previous alkaline treatment should be'taken into. account in settling the alkalinecontent of-the saiddeveloper. Thealkaline intermediate treatment may even be carriedout in such a manner that the total quantity of alkali required for the coupling is added to the copy, in which case the alkali can be omitted from the developer, a variation of the technique which has the advantage that the developer is then less liable to deterioration.

For the production of diapositivcs and kinematographic films the diazo film layer may be located on a clear film support. In this form the invention constitutes an entirely new contribution to the art of applying diazotype printing for these purposes. Particularly strong images with good gradations in the denser continuous tones are obtained when the diazo content of the diazo film layer is between 0.8 and 2.0 millimols per square metre.

The film-forming material for the diazo film layer is advantageously a hydrolysed cellulose ester with an average number of acyl groups attached to the OH groups between 0 and 1.5 (triacetate=3.0). Preferably ahydrolysedtcellulose acetate is taken, but other esters, mixtures of esters or mixed esters, for example acetatebutyrates, are also very suitable. Particularly goodresults are obtained when the film-forming material of thediazo film layer consists of a cellulose ester with an acyl content increasingfrom the outsideinwards, the part of the layer which is insoluble in boiling dry acetone being at least 3 g. and at most 15 g. per square metre.

Other substantially hydrophilic materials, such as gelatine of medium softness, partially hydrolysed polyvinyl esters, cellulose film (cellulose hydrate) mounted on a support, may be used for the diazo film layer.

The following examples will serve to illustrate the invention:

Example 1 On a film of cellulose acetate of weight 140 g. persquare metre, having an acetyl content, calculated as combined acetic acid, of about 53% by weight (corresponding to a-numbercf acyl groups of about 2.3) there is cast at 30 C. an emulsion consisting of p-Diazo-di-n-amylaniline chloride g 9 Citric acid g 0.5 Thiourea g 2 Photographic gelatine (No. I 05 of S. A. Soc. des Produits Chimiques Coignet, Division Gelatines, Hasselt and Vilvorde, Brussels) g Water cc 1000 This cast layer is caused to set at 10 C. and then dried in an air current at 50 C. The layer has a thickness of about 8 mu and contains about 1.5 millirnols of diazo compound per square metre. On the light-sensitive diazo'film layerthus formed, a diapositive is copied by'exposure. to the light of a high pressure mercury vapour lamp of 50 watt per linear cm. of luminous length. After the exposure the copy is passed through a chamber containing moist ammonia fumes at 40 C. The film is left in this chamber for 5 seconds. After this, the film is dipped for'60 seconds in the following solution:

Phloroglucinol g 4 Resorcinol g 4 Potassium-tetraborate-pentahydrate g 40 Thiourea g 20 Water cc- 1000 strong brown-image with a richer gradation in the continuous tones, particularly in the dark areas, than would have been obtained without the intermediate treatment with ammonia fumes described above.

Example 2 Paper of Weight 21.0 g. per square metre, which is coated on one side with a cellulose acetat (about 53% of combined acetic acid) layer of about 10 m thickness, which is applied'on the paper by means of an adhesive and deacylated to a depth of about 4- m to an acetyl content'which increases fromthe outside inwards and which,

2) calculated as combined acetic acid, averages about 20% (which corresponds to an average number of acetyl groups attached to the OH groups of about 0.7), is impregnated on the deacylated side of the cellulose acetate layer for 30 seconds with the following solution:

Zinc chloride double salt of p-diazo-di-normal-hexylaniline g 22 Citric acid g 3 Ammonium chloride g 3 Ethyl alcohol (96%) cc 50 Water -Q cc 900 The excess liquid is removed from the cellulose acetate surface, and the material is subsequently dried. It contains about 0.8 millimol of diazo compound per square metre. After exposure under a diapositive, the copy is exposed for 5 seconds to the action of moist ammonia fumes at 40 C. Almost immediately after this, about 9 g. per square metre of the following developer is applied on the copy:

A black image is obtained with a better gradation, particularly in-the denser continuous tones, than would have been obtained without the intermediate treatment with ammonia described above.

In this connection it is to be noted, that the above developer contains only little alkali (only 1% of sodium carbonate), because some alkali had already been added to the image through the previous intermediate treatment with ammonia. if, for the sake of comparison, it were desired to omit this intermediate treatment, it would be necessary to add an extra quantity of alkali (for example in the form of sodium carbonate) to the developer in order to obtain complete development.

Example3 Baryta-coated paper of weight 170 g. per square metre with a' dull white surface is dipped with its baryta-coated side in a solution of of polyvinyl acetate (with a softening point of about 130 C. and a molecular weight of about 60,000 according to osmotic determination) in methyl alcohol, and dried. Thus a hydrophobic layer of a thickness of about 5 m is applied on the baryta-coated surface. It serves to prevent the penetration into the baryta layer of the diazo solution to be applied subsequently. On to this layer there is now cast at 40 C. about 120 cc. of a (colloidal) solution of:

Cellulose acetate of an acetyl content corresponding to about 28% of combined acetic acid (corresponding to an average number of acyl groups attached to the OH groups ofabout 1.1) g 25 Zinc chloride double salt of p-diazo-di-normalbutylaniline g 2 Alum -g 0.15 Ethyl alcohol (96%) cc 500 Water cc 500 The material is cooled to about 10 C., as a result of which the coating sets. It is then dried in an air current at about 50 C. The cellulose acetate film thus formed has a thickness of about 3 ma. The layer contains about 0.7 millimol of the diazo compound per square metre. After exposure under a diapositive there are applied on the image surface about 9 g. per square metre of the following liquid A: Potassium-tetraborate-pentahydrate g 50 Sodium isopropyl-naphthalene-sulphonateg 3 Mono-sodium mono-Z-ethylhexyl sulphate g 3 Water cc 1000 Almost immediately after this, about 9 g. per square metre of the following developer B are applied to the same side:

Phloroglucinol Resorcinol g Thiourea g Potassium hydroquinone-monosulphonate- -g- Sodium isopropyl-naphthalene-sulphonatea Mono-sodium mono-Z-ethylhexyl sulphate 3 Water cc 1000 Example 4 Cellophane of a thickness of 20 my. and of a very uniform structure is dipped for 5 minutes in the following solution:

Zinc chloride double salt of p-diazo-di-normalbutylaniline g 10 Citric acid g 2 Thiourea g 2 Ethyl alcohol (96%) cc 100 Water cc 900 The cellophane is then doctored and dried under tenson.

The content of diazo compound is about 1.0 millimol per square metre spread through the whole film layer.

After exposure under a diapositive, a treatment of 15 seconds in ammonia fumes at 40 C. is applied, and after this treatment the material is developed in a bath of the following composition:

Phloroglucinol g 8 Resorcinol g 8 Thiourea g 30 Sodium hydroquinone-monosulphonate g 1 Sodium isopropylnaphthalene-sulphonate g. 3 Mono-sodium mono-Z-ethylhexyl sulphate g 3 Water cc 1000 An image is obtained the gradation of which is better than that which would have been obtained if the above intermediate treatment with ammonia fumes had been omitted, and the material had been exclusively developed with the stated developer.

In this example the diazo film layer is independent of the film support.

What we claim is:

1. A process for the production of diazotype copies which comprises selectively exposing to light a one-component diazo film layer material so that the diazo compound therein is only partially decomposed at certain areas of said material, said material comprising a diazo film layer that is suitable for development with a liquid and contains a film forming material and a p-aminobenzene diazo compound that yields an active photochemical decomposition product in the sense that a quantity of the solution obtained upon totally decomposing by light all of said compound contained in a weakly acid 0.004 11 aqueous solution of said compound, when mixed with an equal quantity of a 0.004 11 aqueous solution of pdiethylamino benzene diazonium chloride and allowed to stand at 18 C. and at a pH of about 9.5, decomposes at least half of the amount of diazonium chloride in the latter solution within 15 minutes, said diazo compound uponiexposure being capable of reacting with its photochemical decomposition product under alkaline conditions with the efiect that the part of said diazo compound so reacted no longer will couple with an azo coupling component to give a dyestuff; rendering the exposeddiazo ,film layer alkaline to bring about the aforesaid reaction at said certain areas of said layer; and thereafter developing the diazo film layer by treating it with an aqueous solution containing an 2.20 coupling component under such .conditions that said component couples with the remaining part of said diazo compound.

2. A process as described in claim 1, said step of rendering the-exposed diazo film layer alkaline being etfected by contacting said layer with moist ammonia fumes.

3. A process as described in claim 1, said step of rendering the exposed diazo film layer alkaline being effected by applying to said layer a thin layer or" an alkaline liquid.

4. A process as described in claim 1, said step of rendering the-exposed diazo film layer alkaline being effected by applying to said layer a quantity of alkali sufficient for the development of the image, no appreciable quantity of alkali being applied thereto in said developing step.

5.. A process for the production of diapositives and kinematographic films which comprises selectively exposing to light a one-component diazo type film material so that the diazo compound therein is only partially decomposed at certain areas of said material, said material comprising a transparent film support bearing a diazo film layer that is suitable for development with a liquid and contains a film forming material and a paminobenzene diazo compound that yields an active photochemical decomposition product in the sense that a quantity of the solution obtained upon totally decomposing by light all of said compound contained in a weaklyacid 0.004 11 aqueous solution of said compound, when mixed with an equal quantity of a 0.004 n aqueous solution of pdiethylamino benzene diazonium chloride and allowed to stand at 18 C. and at a pH of about 9.5, decomposes at least half of the amount of diazonium chloride in the latter solution within 15 minutes, said diazo compound upon exposure being capable of reacting with its photochemical decomposition product under alkaline conditions with the effect that the part of said diazo compound so reacted no longer will couple with an azo coupling component to give a dyestufi; rendering the exposed diazo film layer alkaline to bring about the aforesaid reaction at said certain areas of said layer; and thereafter developing the diazo film layer by treating it with anaqueous solution containing an azo coupling component'under such conditions that said component couples with the remaining part of said diazo compound.

6. A process for the production of diazotype copies which comprises selectively exposing to light a one-component diazotype film material so that the diazo compound therein isonly partially decomposed at certain areas of said material, said material comprising a diazo film layer that is suitable for development with a liquid and contains a film forming material and an amount in the range of from 0.8. to 2.0 millimols per square meter of a p arninobenzene diazo compound that yields an active photochemical. decomposition product in the sense that a quantity of the solution obtained upon totally decomposing by light all of said compound contained in a weakly acid 0.004 11 aqueous solution of said compound, when mixed with an equal quantity of a 0.004 n aqueous solution of p-diethylamino benzene diazonium chloride and allowed to stand at 18 C. and at a pH of about 9.5, decomposes at least half of the amount of diazonium chloride in the latter solution within 15 minutes, said diazo compoundupon exposure being capable of reacting with its photochemical decomposition product under alkaline conditions with the effect that thepart of said diazo compound so reacted no longer will couple :with an azo coupling component to give a dyestuft; rendermgthe exposed diazo film layer alkaline to bring about the aforeponent under such conditions that said component couples with the remaining part of said diazo compound.

7. A process for the production of diazotype copies which comprises selectively exposing to light a one-component diazotype film material so that the diazo compound therein is only partially decomposed at certain areas of said material, said material bearing a diazo film layer formed of an at least partially hydrolyzed cellulose ester having an average number of acyl groups attached to OH groups in the range from 0 to 1.5, said .film layer being suitable for development with a liquid and containing a p-aminobenzene diazo compound that yields an active photochemical decomposition product in the sense that a quantity of the solution obtained upon totally decomposing by light all of said compound contained in a weakly acid 0.004 11 aqueous solution of said compound, when mixed with an equal quantity of a 0.004 11 aqueous solution of p-diethylamino benzene diazonium chloride and allowed to stand at 18 C. and at a pH of about 9.5, decomposes at least half of the amount of diazonium chloride in the latter solution within 15 minutes, said diazo compound upon exposure being capable of reacting with its photochemical decomposition product under alkaline conditions with the effect that the part of said diazo compound so reacted no longer will couple with an azo coupling component to give a dyestuff; rendering the exposed diazo film layer alkaline to bring about the aforesaid reaction at said certain areas of said layer; and thereafter developing the diazo film layer by treating it with an aqueous solution containing an azo coupling component under such conditions that said component couples with the remaining part of said diazo compound.

8. A process for the production of diazotype copies which comprises selectively exposing to light a one-component diazotype film material so that the diazo compound therein is only partially decomposed at certain areas of said material, said material bearing a diazo film layer formed of a partially hydrolyzed cellulose ester, the acyl content of said layer increasing from the surface thereof inwards and said layer containing between 3 to 15 grams per square meter of material insoluble in boiling dry acetone, said diazo film layer being suitable for development with a liquid and containing a p-aminobenzene diazo compound that yields an active photochemical decomposition product in the sense that a quantity of the solution obtained upon totally decomposing by light all of said compound contained in a weakly acid 0.004 in aqueous solution of said compound, when mixed with an equal quantity of a 0.004 11 aqueous solution of p-diethyl amino benzene diazonium chloride and allowed to stand at 18 C. and at a pH of about 9.5, decomposes at least half of the amount of diazonium chloride in the latter solution within 15 minutes, said diazo compound upon exposure being capable of reacting with its photochemical decomposition product under alkaline conditions with the effect that the part of said diazo compound so reacted no longer will couple with an azo coupling component to give a dyestuff; rendering the exposed diazo film .layer alkaline to bring about the aforesaid reaction at said certain areas of said layer; and thereafter developing the diazo film layer by treating it with an aqueous solution containing an azo coupling component under such conditions that said component couples with the remaining part of said diazo compound.

9. A process for the production of a diazotype copies which comprises selectively exposing to light a onecomponent diazotype film material so that the diazo compound therein is only partially decomposed at certain areas of said material, said material comprising a .diazo in which X is an anion and R1 and R2 are alkyl radicals together having a total of to 12 carbon atoms, each alkyl radical having at least four and at most seven carbon atoms, and not more than one of the two alkyl radicals having a side chain attached to the alpha carbon atom, said diazo compound upon exposure being capable of reacting With its photochemical decomposition product under alkaline conditions with the effect that the part of said diazo compound so reacted no longer will couple with an azo coupling component to give a dyestuif; rendering the exposed diazo film layer alkaline to bring about the aforesaid reaction at said certain areas of said layer; and thereafter developing the diazo film layer by treating it with an aqueous solution containing an azo coupling component under such conditions that said component couples with the remaining part of said diazo compound.

10. A process for the production of diazotype copies which comprises selectively exposing to light a one-component diazotype film material so that the diazo compound therein is only partially decomposed at certain areas of said material, said material comprising a diazo film layer that is suitable for development with a liquid and contains a film forming material and a salt of p-diazo-di-nhexylaniline, said diazo compound upon exposure being capable of reacting with its photochemical decomposition product under alkaline conditions with the effect that the part of said diazo compound so reacted no longer Wiil couple with an azo coupling component to give a dyestuff; rendering the exposed diazo film layer alkaline to bring about the aforesaid reaction at said certain areas of said layer; and thereafter developing the diazo film layer by treating it with an aqueous solution containing an azo coupling component under such conditions that said component couples with the remaining part of said diazo compound.

11. A process for the production of diazotype copies which comprises selectively exposing to light a one component diazotype film material so that the diazo compound therein is only partially decomposed at certain areas of said material, said material comprising a diazo film layer that is suitable for development with a liquid and contains a film forming material and a salt of p-diazodi-n-amylaniline, said diazo compound upon exposure being capable of reacting with its photochemical decomposition product under alkaline conditions with the effect that the part of said diazo compound so reacted no longer Will couple with an azo coupling component to give a dyestuff; rendering the exposed diazo film layer alkaline to bring about the aforesaid reaction at said certain areas of said layer; and thereafter developing the diazo film layer by treating it with an aqueous solution containing an azo coupling component under such conditions that said component couples with the remaining part of said diazo compound.

12. A process for the production of diazotype copies which comprises selectively exposing to light a one component diazotype film material so that the diazo compound therein is only partially decomposed at certain areas of said material, said material comprising a diazo film layer that is suitable for development with a liquid and contains a film forming material and a salt of p-diazodi-n-butylaniline, said diazo compound upon exposure being capable of reacting with its photochemical decomposition product under alkaline conditions with the effect that the part of said diazo compound so reacted no longer will couple with an azo coupling component to give a dyestuif; rendering the exposed diazo film layer alkaline to bring about the aforesaid reaction at said certain areas of said layer; and thereafter developing the diazo film layer by treating it with an aqueous solution containing an azo coupling component under such conditions that said component couples with the remaining part of said diazo compound.

References Cited in the file of this patent UNITED STATES PATENTS 1,821,281 Van Der Grinten Sept. 1, 1931 1,967,371 Schmidt et al. July 24, 1934 2,066,918 Von Poser et a1 Jan. 5, 1937 2,067,690 Alink et al. Jan. 12, 1937 2,209,087 Leuch July 23, 1940 2,311,016 Alink et al. Feb. 16, 1943 2,336,309 Snell et a1. Dec. 7, 1943 2,532,126 Slifkin Nov. 20, 1950 2,542,716 Slifkin Feb. 20, 1951 2,560,137 Slifkin July 10, 1951 2,659,672 Leuch Nov. 17, 1953 FOREIGN PATENTS 425,235 Great Britain Mar. 11, 1935 644,493

Great Britain Oct. 11, 1950 

1. A PROCESS FOR THE PRODUCTION OF DIAZOTYPE COPIES WHICH COMPRISES SELECTIVELY EXPOSING TO LIGHT A ONE-COMPONENT DIAZO FILM LAYER MATERIAL SO THAT THE DIAZO COMPONENT THEREIN IS ONLY PARTICALLY DECOMPOSED AT CERTAIN AREAS OF SAID MATERIAL, SAID MATERIAL COMPRISING A DIAZO FILM LAYER THAT IS SUITABLE FOR DEVELOPMENT WITH A LIQUID AND CONTAINS A FILM FORMING MATERIAL AND A P-AMINO BENZENE DIAZO COMPOUND THAT YIELDS AN ACTIVE PHOTOCHEMICAL DECOMPOSITION PRODUCT IN THE SENSE THAT A QUANTITY OF THE SOLUTION OBTAINED UPON TOTALLY DECOMPOSING BY LIGH ALL OF SAID COMPOUND CONTAINED IN A WEAKLY ACID 0.004 N AQUEOUS SOLUTION OF SAID COMPOUND, WHEN MIXED WITH AN EQUAL QUANTITY OF A 0.004 N AQUEOUS SOLUTION OF PDIETHYLAMINO BENZENE DIAZONIUM CHLORIDE AND ALLOWED TO STAND AT 18* C. AND AT PH OF ABOUT 9.5, DECOMPOSES AT LEAST HALF OF THE AMOUNT OF DIAZONIUM CHLORIDE IN THE LATTER SOLUTION WITHIN 15 MINUTES, SAID DIAZO COMPOUND UPON EXPOSURE BEING CAPABLE OF REACTING WITH ITS PHOTOCHEMICAL DECOMPOSITION PRODUCT UNDER ALKALINE CONDITIONS WITH THE EFFECT THAT THE PART OF SAID DIAZO COMPOUND SO REACTED NO LONGER WILL COUPLE WITH AN AZO COUPLING COMPONENT TO GIVE A DYESTUFF; RENDERING THE EXPOSED DIAZO FILM LAYER ALKALINE TO BRING ABOUT THE AFORESAID REACTION AT SAID CERTAIN AREAS OF SAID LAYER; AND THEREAFTER DEVELOPING THE DIAZO FILM LAYER BY TREATIN IT WITH AN AQUEOUS SOLUTION CONTAINING AN AZO COUPLING COMPONENET UNDER SUCH CONDITIONS THAT SAID COMPONENT COUPLES WITH THE REMAINING PART OF SAID DIAZO COMPOUND. 